Respirator hoods are known in the art and take many shapes and forms. The hoods generally contain an air impermeable enclosure that surrounds the user's head and neck and a filter system that clears the incoming air of any toxic contaminants.
Some hood designs provide an air impermeable enclosure that forms a tent-like structure around the head of the user and the filter system is enclosed within the enclosure. Other hoods known in the art have externally located filter systems.
Respirator hoods generally include a filter canister, for filtering the ambient air, that is in the shape of a can. U.S. Pat. No. 6,041,778 includes such a canister that is used in combination with a hood. These types of units can be awkward for a user and provide a bulky device that may be unevenly weighted by the canister, causing the hood to slip or move which may allow non-filtered air to enter the hood.
Many prior art hoods include several pieces that require precise placement when a user is donning the hood. Such devices may not be appropriate for emergency use since a user will be required to quickly and precisely place the hood over their head with the minimum amount of adjustment and rearrangement possible.